heating AUDI A4 1998 B5 / 1.G ATQ Engine Additional Signals Testing Workshop Manual

24-173

Test sequence

- Connect VAS5051 tester or VAG1551 scan tool
and select the control module for engine
electronics using "address word" 01 Page 01
-
9 .

Engine must run at idle for this.Rapid data transfer
HELP
Select function XX

When indicated on display:
- Press buttons -0- and -8- to select "Read Measuring Value Block" and
press -Q- button to confirm input.
Read Measurin
g Value Block
Q
Input display group number XXX

When indicated on display:
- Press buttons -0-, -5- and -0- to select "display group number 050" and
press -Q- button to confirm input.
Read Measuring Value Block 50
1
2
3
4

Indicated on display: (1 thru 4 display fields) - Switch A/C system off.

Specified value in display field 4: Compr. OFF
- Switch A/C system on using "Auto" button and adjust A/C system to
maximum cooling or heating power. Compressor must run.
Specified value in display field 4: Compr. ON
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- If there are no malfunctions in the wiring, check
function of A/C system.

Repair Manual, Heating & Air Conditioning, Repair Group 01

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24-175

A/C system signal, checking

The A/C system signal notifies the Engine
Control Module (ECM), that the A/C system
requires a higher idle speed to achieve the
desired interior temperature (regardless of
whether heating or cooling is required).
The increase in idle speed based on presence of
the A/C system signal is control module
dependent and occurs only in vehicles with All
Wheel Drive (AWD) and manual transmission.

Test sequence

- Connect VAS5051 tester or VAG1551 scan tool
and select the control module for engine
electronics using "address word" 01 Page 01
-
9 .

Engine must run at idle for this.Rapid data transfer
HELP
Select function XX

When indicated on display:
- Press buttons -0- and -8- to select "Read Measuring Value Block" and
press -Q- button to confirm input.
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24-177

- Check the following wire connection for open
circuit and short circuit to Ground (GND) and B+:

Test box
VAG1598/31
Socket
A/C control
head -E87-
Terminal
40 Electrical Wiring Diagrams,
Troubleshooting & Component
Locations binder

- Repair open circuit or short circuit if
necessary.

- If there are no malfunctions in the wiring, check
function of A/C system.

Repair Manual, Heating & Air Conditioning,
Repair Group 01

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yp
e=re
pair&id=AUDI.B5.FU05.24.6